Heating apparatus and method



March 28, 1967 J. J. FANNON, JR 3,311,156

HEATING APPARATUS AND METHOD Original Filed Aug. 18, 1960 s Sheecs-Sheet 1 INVENTOR John J.Fonnon,Jr.

Win 4 ATM March 8, 1967 .1. J. FANNON, JR

HEATING APPARATUS AND METHOD Original Filed Aug. 18, 1960 5 Sheets-Sheet 2 R M 0 mm vcm n h o J BIZ BIO

DBBO'Q A ,ymym, yak/M5 ATTOR EYS United States Patent 3,311,156 HEATING PARATUS AND METHGD John J. Fannon, .lr., Grosse Pointe Park, Mich, assignor,

by mesne assignments, to Fostoria-Fannon, Inc., a corporation of Uhio Original application Aug. 13, 1960, Ser. No. 50,421, now Patent No. 3,228,113, dated Jan. 11, 1966. Divided and this appiieation Aug. 25, 1965, Ser. N0. $2,477 8 Claims. (Cl. 15899) This application is a division of application No. 50,421 filed Aug. 18, 1960, by John I. Fannon, In, which is now Patent No. 3,228,113.

The present invention relates to infrared generators or burners and, more specifically, to infrared generators of the combustion type. These infrared generators are particularly adapted for use in multiple generator banks or in close proximity to reflective surfaces or other circumstances where overheating is apt to occur though they need not necessarily be so employed.

The combustion type infrared generators or burners heretofore constructed, such as those designed in accord with the principles of U.S. Patent No. 2,775,294 issued Dec. 25, 1956, to G. Schwank, have been designed and intended for use individually as space heaters rather than for use in banks of large numbers of heaters or in close proximity to a reflective element or work piece to be heated. In prior art ceramic tile burners such as those disclosed in the Schwank patent, the ceramic tiles are recessed Within and surrounded by a metal flange portion of the burner housing. In normal use of such infrared generators, the housing is normally exposed to ambient air which is effective to cool the housing within acceptable limits; and neither the housing nor the radiant Wall of the generator is subjected to any appreciable reflected heat from objects being irradiated.

However, when a plurality of such ceramic tile burners are placed in juxtaposition in a bank, the ceramic surfaces of adjacent burners are separated only by gaps formed by the abutting housing flanges; and circulation of ambient air between adjacent burners is negligible. Moreover, when a bank of such burners is mounted in close proximity to the surface of a work piece being irradiated, a large amount of heat is reflected back against the burners. The reflected heat which impinges upon the radiant faces of the burners merely increases the operating temperature of the radiant faces and produces greater efliciency of the overall operation. However, the reflected heat which impinges upon any portion of the burner in heat conductive relation to the burner housing results in overheating of the housing, warping of the interior bafiies, and, in certain instances, ignition of the premixed gas and air within the plenum behind the radiant faces of the generators. In addition, with large numbers of infrared generators mounted in a bank, ambient air could not be relied upon to maintain the generator housings cool even if these housings could be fully exposed. This is because in heating apparatus of the type in which such burner banks are typically employed, the normal circulation of ambient air is materially impeded due to the necessity of providing air ducts above the burner housings. Consequently, prior art combustion type infrared generators are not well suited for use in banks or in close proximity to reflective work pieces.

It is a primary object of the present invention to provide infrared generators of improved construction in which overheating of the burner housings and concomitant danger of combustion within the plenums is precluded even though the infrared generators are utilized in a manner or in an environment in which overheating would normally occur.

A further important object of this invention is to proice vide gas burning infrared generators of improved construction which are particularly adapted for use in irradiating heat reflective work pieces in close proximity to the radiant face of the generator without'overheating the generator housing structure.

It is another important object of this invention to provide gas burning infrared generators of improved construction which can be arranged in banks formed of a large number of generators juxtaposed in side-by-side and end-to-end relation Without danger of overheating the generator housings.

Another related and more specific object of the present invention is the provision of novel, improved infrared generators in which overheating of the generator housing is precluded by thermal isolation of the radiants from the housing.

A further specific object of this invention is to provide novel, improved, gas burning infrared generators of the perforated ceramic tile type in which the ceramic tiles are mounted in thermally isolated relation from the plenum defining generator housing.

Yet another specific object of this invention is to provide novel, improved, gas burning infrared generators adapted to withstand high degrees of reflected radiation and having components interposed between the radiant wall and a source of premixed gas vand air to prevent flame from flashing back to the source even though the radiant wall is overheated due to the reflection of excessive heat reflection onto it.

A subsidiary object of this invention is to provide improved gas burning infrared generators of the type specified in the preceding object in which the radiant wall or flashback preventing members or both are perforated ceramic tile or multiple ply radiant screen assemblies of the type in which the openings of the intermediate screen are of greater size than those of the interior and exterior screens and the latter are of substantially equal mesh.

A further important object of this invention is to provide improved large radiant area heaters formed of one or more rows of juxtaposed infrared generators in which the radiant faces of adjacent generators are sufiiciently.

close that ignition of one generator can be effected by propagation of flame from an adjacent ignited generator.

A further important and specific object of this invention is to provide novel improved gas burning infrared generators having a perforated radiant wall and a housing structure cooperating with said wall to define a plenum in which the projection of the profile of said housing upon the plane of said wall falls within the confines of the profile of said wall so that said wall shields the radiant face from radiation reflected from the object being irradiated by the radiant face of the wall.

Other objects, additional advantages, and further novel features of the present invention will become more fully apparent by reference to the appended claims and as the following detailed description and discussion proceeds in reference to the accompanying drawings, wherein:

FIGURE 1 is a side view, partially in section, of an improved infrared generator constructed in accord with the principles of the present invention;

FIGURE 2 is a bottom view of the burner of FIG- URE 1;

FIGURE 3 is a fragmentary sectional view of the burner of FIGURE 1, taken substantially along line 3-3 of FIGURE 1;

FIGURE 4 is a fragmentary view illustrating a modification of the generator shown in FIGURE 1;

FIGURE 5 is a sectional view along line 5-5 of FIG- URE 4;

FIGURE 6 is a fragmentary longitudinal sectional view through an infrared generator constituting a further modification of the burner of FIGURE 1;

FIGURE 7 is a fragmentary longitudinal section through a gas burning infrared generator utilizing a three ply, screen type radiant wall in accord with the present invention;

FIGURE 8 is a View similar to FIGURE 7 of a further embodiment of the invention utilizing a pair of spaced, multiple ply screen walls;

FIGURE9 is a view similar to FIGURE 7 of a further embodiment of the invention utilizing an exterior ceramic tile and a multiple ply screen interior wall; and

FIGURE 10 is a view similar to FIGURE 7 of a further embodiment of this invention utilizing an exterior multiple ply screen wall with an interior ceramic tile wall.

First generator embodiment Referring now to the drawing, the detailed construction of a preferred form of combustion type infrared generator 500 is illustrated in FIGURES 1, 2, and 3. As is shown therein, the radiant wall 699 of the infrared generator 500 is defined by a plurality of juxtaposed ceramic tiles 700 through 714 (FIG. 2) supported at their marginal edges with their bottom surfaces lying in a common plane by a frame 716 preferably formed of stainless steel and with a channel-like cross section as illustrated in FIGURE 3. A continuous band 718 of highly temperature resistant thermal insulating material, such as Fiberfrax, is interposed between the exterior side wall surfaces 720 of the peripheral ceramic tiles such as 708 and the base wall of the channel shaped frame member 716. The ceramic tiles 700-714 are preferably of the form illustrated in the aforesaid Schwank patent, but may be of the construction illustrated in copending application Ser. No. 32,136, filed July 15, 1960, by Konrad Bauer for Radiant Burners, which is now abandoned.

Infrared generator 500 is provided with a suitable longitudinally elongate plenum defining housing structure 722 having a central inlet opening 724 through which premixed gases fuel and air are introduced and an internal longitudinally elongate chamber 726 defining a plenum' Housing 722, which is normally formed of sheet steel or as a ferro-metallic casting, and the plenum interior baffle construction is substantially identical with that disclosed in application Ser. No. 577,762, filed Apr. 12, 1956 by Prince et al.. for Radiant Burner, which was c'opending with the parent application and is now abandoned.

Along each longitudinal edge of the open bottom of housing 722 is a laterally extending integral flange 728, best illustrated in FIGURE 3. The radiant wall defined by the tiles 700-714 assembled within the frame 716 is mounted over the bottom opening of housing 722, the margin of which is defined by flange 728, and by a plurality of mounting assemblies 730, the details of which are best illustrated in FIGURE 3.

As shown in the latter figure, the mounting assemblies 730 each comprise a metal clip 732 formed of stainless steel and having a side wall 734, a bottom wall 736, a top wall 738, and an upturned projection 740. The projection740 extends within plenum 726 in spaced relation to the interior of the wall of housing 722. The top wall 738 is parallel to the bottom face of flange 728 and is spaced in thermally isolated relationship therefrom by a continuous thermal insulating gasket 742 formed of Fiberfrax or other suitable material interposed therebetween.

Walls 738, 734, and 736 define a channel closely surrounding the exterior of channel shaped frame 716 and providing a support therefor. Bottom wall 736 is formed with an end slot 744 which surrounds but does not contact a mounting screw 746. The threaded shank 748 of mounting screw 746 extends from its head 758 seriatim through an aperture in a large mesh screen 752, the purpose of which will be explained presently, a spacer 754, a nut 756 with which it'is in threaded engagement, the slot 744 in the bottom wall 736 of bracket 732, a sub.- stantially semi-arcuate notch defined by the co-acti'on of corner quarter arcuate notches 758 of tiles 780-714, an aperture 760 in the top wall 738 of bracket 732 in spaced relation therewith, an aligned aperture in gasket 742, and an aligned aperture in housing flange 728 into threaded engagement with a nut 762 on the top of flange 728. By cooperative adjustment of nuts 756 and 762 along threaded shank 7 48 of screw 746, frame 716 can be firmly clamped between walls 738 and 736 of clamp bracket 732 and bracket 732 and frame 716 firmly secured to flange 728 of housing 722.

In this construction, ceramic tiles 7 88-714- extend over flange 728 of housing 722 to substantially completely shield the entire housing, including flange 728, from the effect of any radiant energy reflected back toward the radiant wall defined by tiles 780-714. Tiles 788-714 are completely thermally isolated from housing 722 and extend substantially to the marginal edge of the entire infrared generator assembly 500 so that a similar generator can be placed in juxtaposition therewith either in side-by-side or end-to-end relation with little or no space left therebetween. A bank of infrared generators of this type can therefore readily be ignited by flame propagation from one to an adjacent juxtaposed generatOl.

As is best shown in FIGURE 1, screen 752 is a wide mesh screen disposed in parallel relationship to and beneath the radiant wall 699 defined by ceramic tiles 768-714 to prevent particles of ceramic material from dropping onto the work pieces if the tiles deteriorate after extended use. In addition, screen 752 increases the amount of radiation emitted due to the rer-adiation from the screen wire, which reaches a higher temperature than the ceramic blocks.

Second generator embodiment A modified mounting assembly 770 for securing tiles 781L714, their supporting frame 716, and interposed gasket 718 to flange 728 of housing 722 is illustrated in FIGURES 4 and 5. In this embodiment, frame 716 is supported by a plurality of brackets 772 each having a bottom wall 774 slotted at 776, a side wall 778, and a top wall 780 lying above flange 728. A suitable thermal insulating gasket 782 is interposed between the top of frame 716 and flange 72 8, and a further suitable thermal insulating gasket 784 is interposed between the top wall 780 of bracket 772 and flange 728 of housing 722. A mounting screw 786, provided with a threaded shank 788, extends from its head 798 seriatim through slot 776, the notches 758 in the tiles, gasket 782, housing flange 728, gasket 78:; and top wall 780 of the bracket 772 into threaded engagement with a nut 792. It will be noted that the housing flange 728 is thermally isolated from bracket 772, from frame 716, from screw 786, and tiles 700-714. The shank 788 of screw 786 is in spaced relation to both the tiles and housing flange 728.

With the foregoing exceptions, the embodiment of FIGURES 4 and 5 is the same as the embodiment of FIGURES 1-3.

Third generator embodiment FIGURE 6 illustrates an embodiment of the invention adapted for extremely high temperature operation as in glass kilns, for example. In this embodiment a pair of walls 880 and 802 are mounted over the side wall opening 804 of a plenum chamber 806 formed by a burner housing 808, which is similar to housing 722. Walls 808 and 802 are both formed of ceramic tiles, wall 802 being the exterior wall the outer surface 810 of which is heated to visible radiance by the combustion of gaseous fuel and air on its surface 810 and in the outlet ends of its transverse perforations 812. The ceramic tiles which form wall 802 may be of the type illustrated in the aforesaid Schwank patent or may be of the diagonally transversely perforated type illustrated and claimed in the Bauer application mentioned above.

The tiles of walls 800 and 802 are supported in a stainless steel frame structure 816 of channel shaped cross section and are thermally insulated therefrom by suitable gaskets 818 and 820 for wall 802 and gasket 822 for Wall 800. Frame 8115 is thermally insulated from the flange 824- of housing 808 by an interposed gasket 826.

The size of the perforations through the inner ceramic wall 800 are preferably smaller than those of through wall 802 but, if oppositely diagonally inclined perforations are provided as indicated in FIGURE 6, may be of equal size. The spacing between the adjacent parallel surfaces of walls 800 and 802 is preferably in the order of one-eight inch to define a chamber therebetween. Interior wall 800 provides proper isolation of the intermixed combustible gas and air within plenum 806 from the effects of the reflected radiant energy upon the exterior tile of wall 802, thereby minimizing the possibility of flashback, and insures complete thermal isolation of housing 808 from any reflected radiation.

Fourth generator embodiment FIGURE 7 illustrates a modification of the burner of FIGURES l3 in which a multiple ply screen assembly 830 is substituted for the ceramic tile radiant wall 699 of infrared generator 500. Multiple ply screen assembly 830 comprises an inner screen 832, an outer screen 834 of substantially the same mesh as screen 832, and an intermediate screen 836, which has substantially larger apertures and heavier gauge wire than screens 832 and 834 and maintains screens 832 and 834 in spaced relation. In practice, screens 832 and 834 may have 40 x 40 apertures per square inch; and screen 836 may have x 10 apertures per square inch.

The margins of screens 832, 834-, and 836 are anchored in a metal frame structure 838, which is secured to housing 722 by screws 840. Thermal isolation of screen assembly 830 from housing 722 is provided by a gasket 842, and thermal isolation of frame structure 838 from screw 840 is provided by a tubular insulator 844 and a gasket 846.

Fifth generator embodiment FIGURE 8 illustrates an infrared generator adapted for high temperature use like that of FIGURE 6. This infrared generator utilizes a pair of parallel multiple ply screen assemblies 850 and 852, each of which may be of the same construction as the screen assembly 838 of FIGURE 7. The screen assemblies are mounted in parallel relation within a channel shaped frame 854.

Thermal isolation of screen assembly 850 from screen assembly 852 is maintained by an interposed gasket 856; thermal isolation of screen assembly 858 from frame 854 is provided by a gasket 858; and thermal isolation of screen assembly 852 from frame assembly 854 is effected by a gasket 860. Frame 854 is thermally isolated from housing 722 by a gasket 862.

Frame 854 is fixed to housing 722 by a plurality of mounting screws 864 extending as illustrated through the top and bottom Walls of frame 854 and through the frames of screen assemblies 858 and 852 into threaded engagement with the housing 722. Thermal isolation of assemblies 850 and 852 from screw 864 is maintained by tubular insulators 866 and 868.

Sixth generator embodiment FIGURE 9 illustrates a further high temperature application infrared generator utilizing an interior wall 870 of the multiple ply screen type as described in reference to FIGURE 7 and an exterior wall 872 which is perforated ceramic tile of the type described in the aforesaid Schwank patent. Walls 870- and 872 are maintained in mutual isolation by an interposed gasket 874, and interior wall 870 is isolated from housing 722 by gasket 876. Walls 870 and 872 are attached to housing 722 by screws 878, which are thermally isolated from walls 870 and 872 by tubular insulators 8'80 and 882.

Seventh generator embodiment FIGURE 10 illustrates a further high temperature embodiment of the invention which is identical to that shown in FIGURE 9 except that the positions of walls 870 and 872 are reversed so that multiple ply screen wall 870 is the exterior wall which is heated to radiant temperature and ceramic tile wall 872 is the interior wall which maintains thermal isolation between the exterior wall and plenum 726. In the embodiment of FIGURE 10, as in the embodiment of FIGURE 6, the spacing between the exterior and interior walls should be in the order of oneeighth of an inch; and the perforations of the interior wall should be of lesser cross section than the perforations through the exterior wall (similar dimensions should be adhered to in the fifth and sixth burner embodiments described above).

The invention may be embodied in other specific forms without departing from the spirit or essential charac teristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by Letters Patent is:

1. In an infrared generator of the combustion type:

(a) a housing defining a supply plenum for a combustible mixture of fuel and air, one side of said housing being open;

(b) a perforate radiant wall adapted to be heated to incandescence by combustion of the fuel-air supplied from said plenum thereadjacent; and

(c) means for so supporting said radiant wall from said housing that said wall spans the open side of said housing, comprising frame means extending around said wall and supporting the wall by the edge portions thereof, support means embracing said wall supporting frame means, fastening means fixing said support means to the housing, and insulating means between said support means and said housing to thermally isolate said housing from said radiant wall.

2. In an infrared generator of the combustion type:

(a) a housing defining a supply plenum for a combustible mixture of fuel and air, one side of said housing being open and there being a flange around said housing at the open side thereof;

(b) a perforate radiant wall adapted to be heated to incandescence by combustion of the fuel-air supplied from said plenum thereadjacent; and

(0) means for so supporting said radiant Wall from said housing that said wall spans the open side of said housing, comprising a frame extending around said wall and embracing the edge portions thereof, whereby said wall is supported within said frame; clips embracing said frame at intervals therealong, fastening means fixing said clips to the housing flanges, and insulating members between said clips and said flange to thermally isolate said housing from said radiant wall.

3. The infrared generator of claim 2, together with:

(a) a reradiator of generally the same overall dimensions as said radiant wall; and

(b) means supporting said reradiator from said housing flange in parallel spaced relation to the radiant Wall comprising the fastening means which fix the frame supporting clips to said flange and spacer means interposed between said radiant wall and said reradiator.

4. The infrared generator of claim 2, together with an insulating member between the radiant wall and the frame therearound.

5. In an infrared generator of the combustion type:

(a) a housing defining a supply plenum for a combustible mixture of fuel and air, one side of said housing being open and there being a flange around said housing at the open side thereof;

(b) a perforate radiant wall adapted to be heated to incandescence by combustion of the fuel-air supplied from said plenum thereadjacent; and

(0) means for so supporting said radiant Wall from said housing that said wall spans the open side of said housing, comprising a frame, said frame having a base portion and leg portions engaging the opposite side of the radiant wall, whereby said wall is supported within said frame, frame supporting clips at intervals therealong, each said clip having first and second legs abutting one of the legs and the base of said frame and a third leg adapted to be disposed adjacent the housing flange, and means fixing said clips to said flange including elongated fasteners extending through said clips and said flange and retainers on said fasteners and cooperating therewith to bias said clips toward said flange; and insulating members between said clips and said flange to thermally isolate said housing from said radiant wall.

6. The infrared generator of claim 5, wherein said clips have fourth legs which are disposed within the housing to locate said. frame and the radiant wall supported thereby laterally relative to said housing.

7. The infrared generator of claim 5, together with a reradiator substantially contiguous in area with said radiant wall, said elongated fasteners extending through said CJI reradiator and thereby supporting it from the housing flange, and spacers journalled on said fasteners and maintaining said reradiator in spaced relation to said radiant wall.

8. The infrared generator defined in claim 1, wherein said radiant wall is formed by a plurality of juxtaposed transversely perforated ceramic tiles.

References Cited by the Examiner UNITED STATES PATENTS 1,074,110 9/1913 Eyfe 158-99 1,304,755 5/1919 Ellis 15899 3,027,936 4/1962 Lamp 1581 14 X 3,084,736 4/ 1963 Mentel et al. 1584-114 3,114,363 12/1963 Koltun 15899 X FOREIGN PATENTS 239,274 6/ 1962 Australia.

792,164 10/1935 France. 1,136,829 1/1957 France.

763,402 12/ 1956 Great Britain.

464,439 7/1951 Italy.

521,090 3/1955 Italy.

529,640 6/ 1955 Italy.

340,030 9/ 1959 Switzerland.

JAMES W. WESTHAVER, Primary Examiner.

FREDERICK L. MATTESON, JR., Examiner.

H. B. RAMEY, Assistant Examiner. 

1. IN AN INFRARED GENERATOR OF THE COMBUSTION TYPE: (A) A HOUSING DEFINING A SUPPLY PLENUM FOR A COMBUSTIBLE MIXTURE OF FUEL AND AIR, ONE SIDE OF SAID HOUSING BEING OPEN; (B) A PERFORATE RADIANT WALL ADAPTED TO BE HEATED TO INCANDESCENCE BY COMBUSTION OF THE FUEL-AIR SUPPLIED FROM SAID PLENUM THEREADJACENT; AND (C) MEANS FOR SO SUPPORTING SAID RADIANT WALL FROM SAID HOUSING THAT SAID WALL SPANS THE OPEN SIDE OF SAID HOUSING, COMPRISING FRAME MEANS EXTENDING AROUND SAID WALL AND SUPPORTING THE WALL BY THE EDGE PORTIONS THEREOF, SUPPORT MEANS EMBRACING SAID WALL SUPPORTING FRAME MEANS, FASTENING MEANS FIXING SAID SUPPORT MEANS TO THE HOUSING, AND INSULATING MEANS BETWEEN SAID SUPPORT MEANS AND SAID HOUSING TO THERMALLY ISOLATE SAID HOUSING FROM SAID RADIANT WALL. 